Investigation of the impact of annealing on the structural, optical and morphological evolution of mixture-phase ALD-TiO2 films containing brookite

A detailed characterization of TiO2 films grown on n-Si and glass substrates by atomic layer deposition technique was reported. Films were annealed in a wide temperature range (300-1100 degrees C) to give more information about the effect of crystal structure evolution on morphological and optical properties. The structural evolutions were investigated by grazing incidence X-ray diffraction. It was determined that the annealed films have "mixed phase" structure containing "brookite" phase even at high annealing temperatures. Optical properties were studied using UV-Vis and band gaps of films were calculated from Kubelka-Munk function and Tauc equation. Calculations were revealed that the films have minimum 3.0 eV (n-Si) and 2.95 eV (glass) optical band gap values for indirect transitions. Also, morphological properties of the films were investigated by atomic force microscopy and results present that the mixed phase structure an effect on the morphology of the TiO2 films as in all features.